Cortisol and epinephrine differentially influence T cell subpopulations. Mean (± SEM) numbers of (A,E) naive (CD45RA⁺CD62L⁺), (B,F) central memory (CD45RA⁻CD62L⁺), (C,G) effector memory (CD45RA⁻CD62L⁻), and (D,H) effector (CD45RA⁺CD62L⁻) CD4⁺ (left) and CD8⁺ (right) T cells after a 30-minute intravenous infusion () of placebo (sodium chloride, ○), cortisol (●), and epinephrine (); n = 10, *P < .05, **P < .01, ***P < .001, pairwise comparison between cortisol/placebo conditions (A-C,E-G), and epinephrine/placebo conditions (H) at single time points. Bar charts represent percentage changes in (I) CD4⁺ and (J) CD8⁺ T cell subsets 180 minutes after cortisol () and 30 minutes after epinephrine infusion (), respectively, compared with placebo (Table 2). *P < .05, **P < .01, ***P < .001, analysis of variance main effect (Cort/Plac, Epi/Plac) and for pairwise comparison of cortisol effects between naive vs central memory, central memory vs effector memory, and effector memory vs effector T cells.